This invention relates to a fluidic control system for manually operated machines and the like.
In manufacturing processes, a machine is often manually loaded and unloaded. Additionally, the operating parts may be manually cleaned and otherwise maintained. Manually operated devices having elements moving in the work area are potentially dangerous to the operating personnel. In the event a control or drive system malfunctions or a human error, the moving work element may strike the arms or body of the personnel in the work area. In particular, cutting or shearing machines, punch presses and the like have a ram die which reciprocates in spaced cycles in a work area. The operating personnel often introduce their hands and arms between the working die and the press bed during the feeding and removal of material. Press control systems, and the like, have, therefore, generally required that the system employ a pair of manually operated electrical controls such as pushbutton switches which are spaced and connected such that the operating personnel must maintain both of his hands in engagement with the respective switches during the time the press work element is moving to engage the work to thereby protect the operator during the hazardous portion of the operating cycle. Such controls generally include a non-tie-down feature which will prevent the operator from otherwise latching one or both switches on in order to increase the work rate or the like. Also, an anti-repeat feature is generally included, that will guarantee that all the switches must be released by the operator and then actuated again in order to initiate a next work cycle of the press. Further, if maximum safety is to be obtained, the system must be failsafe and provide for automatic shutdown in the event of any malfunctioning of the control or operating components.
Although various electrical anti-repeat press control systems have been developed, they require relatively complicated electrical circuit controls, and are characterized by the normal electrical maintenance and failure characteristics.